Story of Psychology - Morton Hunt [147]
We shall therefore be able to know…if one [child] rises above the average level of other individuals considered normal, or if he remains below. Understanding the normal progress of intellectual development among normals, we shall be able to determine how many years such an individual is advanced or retarded. In a word we shall be able to determine to what degrees of the scale idiocy, imbecility, and débilité correspond.28
Defining intelligence in terms of age and assembling a set of cognitive tasks that measured the mental age of a child replaced Galton’s anthropometric testing and became the foundation of the intelligence-testing movement.
After publishing their study, Binet and Simon took into account shortcomings they had discovered and criticisms offered by others and revised the scale extensively in 1908 and again in 1911. These revisions were supplied with scoring information—a set of standards as to the questions and tasks a child of any age should be able to answer and perform. (If 60 to 90 percent of the children at any given age could pass a particular test, Binet and Simon considered it normal for that age.) Here are some of the items in the 1911 scale:29
Three years:
Points to nose, eyes, and mouth.
Repeats two digits.
Enumerates objects in a picture.
Gives family name.
Repeats a sentence of six syllables.
Six years:
Distinguishes morning and evening.
Defines words by use (e.g., “A fork is to eat with”).
Copies a diamond shape.
Counts thirteen pennies.
Distinguishes drawings of ugly and pretty faces.
Nine years:
Gives change out of twenty sous.
Defines words in a form superior to use (e.g., “A fork is an instrument for eating”).
Recognizes the value of nine pieces of money.
Names the months in order.
Answers easy “comprehension questions” (e.g., Q: “When one has missed the train what must one do?” A: “Wait for another train”).
Twelve years:
Resists suggestion. (The child is shown four pairs of lines of different length and asked which is longer in each case; in the last case the lines are the same length.)
Composes a sentence using three given words.
Names sixty words in three minutes.
Defines three abstract words (charity, justice, goodness).
Makes sense out of a disarranged sentence.
The 1908 scale included tests for age thirteen and the 1911 scale for adults; as later researchers would show, the growth of intelligence continues to early adulthood and then ceases.
The 1908 and 1911 revisions were the first functional tests of intelligence validated against classroom performance and “normed” (provided with scores representing the normal level of response at every age). For the first time, psychologists could determine how far, in years, a child’s mental development was behind normal or ahead of it. Binet and Simon said that if the child’s mental age was two or more years below his or her chronological age, the child was likely to require special education. They also defined three levels of retardation in terms of mental ages. The idiot, they said, had a mental age of two or less; the imbecile, between two and seven; and the débile above seven but significantly lower than his or her chronological age.
The weakness in these ratings was that they were fixed mental ages, while nearly all retarded children continue to develop mentally, although at a slower pace than normal. A child of four with a mental age of two is an idiot, but at age eight or ten, though still an idiot, his mental age will probably have reached the four- or five-year-old level.
In 1912 a German psychologist, William Stern, solved the problem by suggesting that if the child’s mental age is divided by its chronological age, the result will be its “mental quotient”30 (soon renamed “intelligence quotient,” or IQ), a ratio that expressed the child’s relative